The findings reported to date from Supporting Healthy Marriage (SHM) and related studies have caused others to conclude that healthy marriage initiates are not effective (Johnson, 2014). After reviewing the prior analyses with SHM data, it is premature to conclude that SHM and related programs are not effective for improving marriages and children's lives. The overall objective of this study is to use advanced longitudinal data analysis (derivatives, differential equations) to test theoretically driven hypotheses regarding how and why family strengthening programs work, and when and for whom these programs are maximally effective. The central hypothesis is that using these advanced methods, which can test more nuanced and overlooked theoretical questions about change processes, will advance the field of family strengthening initiatives forward by uncovering relations that may be masked by traditional statistical methods. The specific aims of the study are: (1) Identify the mechanisms through which family strengthening programs improve children's well-being; (2) Identify the optimal time during children's lives when family strengthening programs provide the maximum benefit for their well-being; and (3) Identify existing family vulnerabilities that may constrain the effectiveness of family strengthening programs for children's well-being. Samples: Supporting Healthy Marriage (SHM) dataset which includes 6298 low income couples and their child. Measures: Marital Quality ? Survey data ? Survey item data reduction ? Observational data Child Outcomes (children's internalizing and externalizing behavior problems and reactions to inter-parental conflict) Parental Psychological Distress Financial Strain/Economic Security Parenting Marital Stability Program Enrollment/Engagement